How clean and safe is it when you format using windows vista disc?

How clean and safe is it when you reformat using windows vista disc?
1. is using the windows vista disc the proper way of reformatting a hdd and installing the same operating system windows vista?

*these are the steps i took*

- place the disc inside my dvd rom, and reboot
- press enter, so it loads to the windows vista page
- when i go to the page that has your hdd options, i click on "format", which only takes around 10 seconds.

By using the windows vista disc, will my hdd be safe and clean if i had virus or malcious trojan worms?

Or should i use a hdd that already has an operating system and then connect my hdd (the one i want to reformat) and once my pc reconize my 2nd hdd, right click on my hdd and click "format"

I mean i did that and took me about 4-5 hours with a 1tb hdd. Using Vista only takes about 10 seconds, doesn't seem like it really cleaned my hdd. Did it?